Scimitar syndrome is a rare malformation of the arterial supply and venous drainage of the lung. We report the case of a fetus that presented with cardiac asymmetry and malposition of the fetal heart. Postnatally, scimitar syndrome was confirmed at cardiac catheterization. Retrospective reconstruction of three-dimensional power Doppler volumes, obtained during fetal life, allowed direct visualization of the abnormal aortopulmonary collateral vessel. This had not been seen on conventional scans. This case demonstrates many of the strengths of three-dimensional sonographic techniques for the delineation of complex vascular anatomy. It confirms that a prospective diagnosis of scimitar syndrome should be possible during fetal life.